Method for forming fibrous mats



Feb. 15, 1955 G. M. LANNAN 2,702,069

METHOD FOR'FORMING FIBROUS MATS Filed Jan. 50, 1951 Z'ShetS-Sheet l INVENTOR. George #1 [0000/7 A TTORNE Ys Feb. 15, 1955 Filed Jan. 30, 1951 G. M. LANNAN METHOD FOR FORMING FIBROUS MATS 2 Sheets-Sheet 2 INVENTOR. George M. [0/7000 BY n W v W AffaEA/KYJ United States Patent METHOD FOR FORMING FIBROUS MATS George M. Lannan, Newark, Ohio, assignor to Owens- Corning Fiberglas Corporation, a corporation of Delaware Application January 30, 1951, Serial No. 208,501 1 Claim. (Cl. 154-28) The present invention relates to a production of mats of fibrous material and more particularly to a process for forming mats of glass fibers.

It is an object of the present invention to provide a process for making fibrous glass mats of haphazardly arranged glass fibers that will be replete with voids or air spaces to obtain high acoustic and thermal insulating properties.

It is a further object of the invention to make mats of fine glass fibers that will be highly resilient, have a high degree of integrity and are highly uniform in character for use as a reinforcement for plastics.

It is another object of the invention to produce fibrous glass mats that, while being resilient, have also a certain resistance to compression, making them suitable for cushioning, padding and as clothing inter-liner material.

A still further object of the present invention is to provide a process for forming mats of fibrous material efficiently at high speed and in an economical manner.

Other objects and purposes of the invention will become apparent during the course of the following description.

In the present invention glass fibers have been selected as one fibrous material particularly adapted for handling in the process and because of their inorganic nature, high strength characteristics and other features inherent in the fibers. Glass in fibrous form may be produced by many well known processes. Glass fibers designated generally by the term glass wool" are usually produced by flowing streams of molten glass and engaging the molten streams in a high speed gaseous blast to attenuate the streams to fibers. Fibers formed in this manner may vary in length from a few inches to many feet and are customarily collected on a moving foraminous belt in the form of a mat or bat. Material of this form has been found useful as thermal and acoustical insulation when impregnated with a binder and molded into substantially rigid or self-sustaining shapes.

A second form in which glass fibers are used commercially includes strands or yarns of continuous length which may be woven into textiles. Glass fibers in this form are produced by flowing streams of molten glass, gathering the streams together to form a strand and winding the strand on a support at a high speed to attenuate the streams to very fine fibers. Each of the streams is continuously attenuated and the strands formed thereby may be produced in unlimited lengths. A binder is usually applied to the strand as it is formed to preserve integrity of the strand and prevent separation of the filaments during later processing operations. The single filaments in the strand may number from 100 to 200 and have a nominal diameter of from .0002 to .0004 inch while single glass wool fibers may average from .0005 to .0006 inch in diameter but may if desired be 'much smaller, say .0003 inch.

Strands formed by the above continuous forming process both in woven and unwoven forms have found great utility as a reinforcement for molding resins and are widely used in laminated plastics because of their high strength, and non-hygroscopic characteristics. In addition, these strands of continuous type fibers may be cut into short lengths to form mats in which the strands are present in the form of haphazardly arranged bundles of fibers.

The present invention not only provides for the production of mats from a single type of fibers but contemplates combining fibers formed by both the glass wool 2,702,069 Patented Feb. 15, 1955 ice . and continuous fiber forming processes. In addition organic fibers may also be processed in accordance with the present invention or combined with the glass fibers.

The glass wool fibers, as an example may be formed in which the present invention may be carried out;

Figure 2 is a side elevational view of a part of the appara tus shown in Figure 1;

Figure 3 is a sectional plan view of the mechanism of Figure 2;

'mat may be dipped in an adhesive solution.

Figure 4 is a vertical sectional view through the picker golls dtaken substantially along the line 4-4 of Figure Figure 5 is a view similarto Figure 4 but showing a modified form of the invention.

This application is a continuation-in-part of my copending aplication Serial No. 758,925, filed July 3, 1947, now Patent No. 2, 589,008.

The present invention is readily adaptable for producing mats of any desired fibrous material which may be either organic or inorganic fibers or a combination of such fibers depending upon the end use of the material.

Combination materials may be produced to provide any desired characteristics inherent in the materials being combined. As an example, mats of glass wool fibers have low tensile strength, particularly when very thin and it is sometimes desirable to incorporate and bond therein high strength continuous type fibers to provide a mat having relatively high tensile strength while retaining me characteristics of the mats of glass wool fibers. The bonding material may be applied by spraying or the Bonding may also be accomplished by mixing with the fibrous material a dry resin which upon the application of heat or in the presence of a solvent becomes softened and adheres the mat fibers together. Such resins may be in either fibrous or powdered form. In addition, the mat material may be bonded by incorporating a small percentage, say 10 percent or so, of continuous type strands which are heavily coated with a heat reactable resin. The resin coated strands are interspersed throughout the mat and upon the application of heat the resin is caused to soften and flow and thereby effect a complete bonding of the mat material.

In general, the steps by which mats are formed in accordance with the present invention will now be described, reference being made especially to Figure l of the accompanying drawings. One apparatus found suitable for the processing of the fibrous material includes a primary fiber opening-and feeding mechanism A. In forming a mat of a single fibrous material the bulk fibers are supplied to the feeder A which delivers a thin layer of the material to the first picking stage B. The fibers which at this point may be in non-uniform clumps or irregular masses are fed into the picking roll which opens or tears apart the masses and separates the fibers into small tufts or bundles of fibers. These opened or partially separated fibers as they are discharged from the picker collect in the form of a loosely felted mat or sheet having a relatively uniform thickness and distribution of fibers.

The mat as it forms is continuously fed to a second picking stage C where the fibers are again separated and recollected. The greater uniformity of the sheet of material thus being fed is transmitted to the final mat so that the resulting product has the highest degree of uniformity in thickness, density and texture. The importance of the two stage picker operation is readily apparent when materials which are dissimilar in character are to be combined into a single mat. The operation of the picking rolls is such that the different materials are mixed and blended into a uniform product.

The mat of material flowing from the stage C comprises an unbonded heterogeneous arrangement of fibers .powder or as a fibrous material which is mixed with the mat fibers before passage through the picker, or the dry powder may be sifted into the formed mat and sub ected to heat to set the adhesive.

After passage of the mat through the oven the mat may be rolled or cutinto sheets for storage or shipment or it may pass directly into other fabricating operations.

Referring particularly to Figure 1 of the drawings the fibrous material is placed in a hopper which forms a part of the feeding mechanism A. A movable belt 11 forms the floor of the hopper 10 and moves the fibers in a rolling motion to a fiber picker belt 12. The movement of the belt 11 provides a continuous feed to the belt 12 as long as any fibrous material remains thereon. The picker belt 12 is provided with a plurality ofspikes or needle points 13 which pick an even mat from the mass in the hopper as it advances and passes it over to a feeder belt 15 which carries the material into the first picking stage mechanism B. As the picker belt 12 conveys the fibrous material upwarda short belt 16 removes any unduly large masses from the belt 12 so that a substantially uniform layer of fibers is carried to the feeder belt 15.

In order to remove the fibrous material from the picker belt 12 as it is carried from thehopper 10 a stripper 18 comprising a plurality of blades 19 of leather, rubber, or the like has been provided. Rotation of the stripper 18 causes the blades l9 or paddles to wipethe material from the spikes 13 so that it is deposited on the feeder belt 15. The feeder belt l5 conveys the fibrous material as a substantially uniform sheet 21 of loosely matted fibers in the direction of the mixing or picker station B. The belt is preferably continuously driven by means of a motor 22 and gear reduction unit 23 through a chain 24 to carry the mat beneath a feed regulating roll 25. The feed roll 25 is weighted to provide tension on the fibers and is mounted on arms 26 pivoted to the framework of the picker mechanism. This mounting permits movement of the roll toward and away from the surface of the feeder belt 15 as mats of varying thickness are fed therebeneath. .As the mat of fibers issues from beneath the roll 25 it is engaged by a picker roll 28 which is cylindrical in form and is provided with rows of pointed spikes or needles 30 which tear small tufts of fibers from the end of the mat 21. The needles 30 are arranged in rows spaced uniformly radially of the roll and the rows are set in staggered relation, consecutive rows being ofiset approximately A of the distance between the needles of each row. With this arrangement of the spikes the fibers are pulled from the mat in a substantially uniform manner.

Rotation of the. roll 28 in a clockwise direction tends to throw the fibers forwardly into a settling chamber 32. Should the spikes 30 of the roll 28 dislodge a greater mass of fibers than normally required, a non-uniform mat would be produced. :To guard against this possibility a second roll 34 is provided. The roll 34 is mounted above the roll 28 and is provided with spikes arranged in uniformly spaced rows about the periphery of the roll. The roll 34 is positioned slightly to the rear of the roll 28 and is also rotated in a clockwise direction. The rolls 28 and 34 are spaced apart only sufficiently to permit clearance of the spikes since the two rolls are rotated at different speeds as will be brought out in detail presently. Any large tufts of fibrous material picked up by the roll 28 and which extend beyond the ends of the spikes 30 will be engaged by the spikes 35 of the other roll and torn apart or thrown rearwardly onto the incoming mat.

Should such a mass of fibers adhere to the spikes 35 and be carried around as the roll rotates, a third roll 38 has been provided. This roll 38 is constructed similarly to the previously mentioned picker rolls and carries spikes 33 arranged in rows about the periphery. The rolls 34 and 38 are mounted in a common horizontal plane and are spaced apart so that the spikes intermesh throughout substantially their entire length. Thus any tuft or mass of fibers carried by or between the spikes 35 are .engaged by the spikes 39. The axial spacing of the spikes carried by each roll are such as to provide a clearance of A; of an inch or less so that the tufts of fibers are completely disrupted and dispersed. The roll 38 is 28. As an example of the relative speeds of the rolls it may be assumed that the roll 28 rotates at the rate of 1200 R. P. M. The roll 34 is geared to rotate at approximately 800 R. P. M. and the roll 38 is geared for rotation at approximately 1600 R. P. M. The speed of rotation of the rolls may be regulated by means of the motor 45 depending upon the type of fibrous material being processed and the facility with which the material is dispersed. f

As the fibers discharged from the picking mechanismenter the settling chamber 32 they are collected on an inclined foraminous belt mounted on rollers 51 for continuous movement. A suction chamber 53 is provided beneath the surface of the belt so that the fibers are drawn downwardly and collect on the belt in the form of a pad 54. The belt 50 or conveyor corresponds substantially to the feeder belt 51 previously described and carries the fibers collected thereon to the second stage picker mechanism C.

The rotation of the picking rolls just described sets up currents of air which move generally in the direction of the rolls causing some of the fibers in the material to be carried thereby. In order to offset this difficulty I have provided air jets 55 arranged above the roll 38 and beneath the roll 28 to direct blasts of air in the direction of the settling chamber 32. This movement of air not only counteracts the tendency of the fibers to follow the surface of the rolls but augments the action of the suction chamber 53 in uniformly dispersing the fibers. The wall 56 which forms the roof of the settling chamber 32 may be suitably curved to provide a streamlined flow to carry the fibers over at least a major portion of the settling area. The wall 56 which may also form a closely fitting cover for the rolls extends forwardly and terminates adiacent the picker mechanism C. It is believed that a more uniform layer of fibrous material may be obtained if the fibers are permitted to float in a circulating air stream before settling to the belt 50.

The pad 54 is fed by the belt 50 into the second stage picking mechanism C, the construction of which is a counterpart of the mechanism B and the parts therein are designated by the same numerals. As the mat 54 is torn apart by the picking rolls the fibers are projected forwardly within a settling chamber 58, the bottom of which is formed by a travelling foraminous belt 59. A suction chamber 60 is provided beneath the belt in the area of the chamber to collect the fibers into the final mat structure. A gate roll 61 is arranged at theend of the settling chamber to initially compress the mat 59 as it is conveyed forwardly.

When it is desired to apply binder to the matted fibers spray guns indicated at 63 are arranged above the mat to apply binder to the surface of the mat or saturate it. Binder may be applied tothe bottom of the mat hv spray guns indicated at 64 arranged at the end of the belt 59 if desired. As an example, the binder may include emulsions of phenol formaldehyde, methyl methacrvlate, polystyrene or polvvinvl acetate. Such materials may be present in the finished product in amounts ranging from 7 /2 to 12 /2 per cent by weight of the fibers.

The binder impregnated mat is then cured or dried by passing the mat through a suitable oven 65 associated with a conveyor flight 66. filitable mechanism may be provided for circulating heated air through the mat to cure the binder thereon. As the mat leaves the oven it may be either coiled into a roll, cut into sheets or passed directly into other fabricating operations.

Mats formed in the present manner may be employed as a base for roll roofing. shingles or siding in which the mat after passing from the present apparatus is impregnated with an asphalt composition and further processed into the desired material.

The modified arrangement of picker rolls shown in Figure 5 results in finer and more drastic picking of the fibrous material. In this arrangement the rolls 128 and 134 are in the same relation as rolls 28 and 34 in the dispersed throughout the depth of the mat.

form of the invention shown in Figures 1 to 4. Rolls 128 and 138 are so related that the teeth 130 and 139 respectively on the two rolls are in intermeshing relation similarly to the teeth 135 and 139 on the rolls 134 and 138. As a result of this relation of the rolls, all material passing between the rolls 128 and 134 receives a final working or picking by the intermeshing teeth of the rolls 128 and 138. The speeds of rotation of the rolls may be the same as those previously mentioned.

The following examples illustrate the operation of the apparatus in connection with the forming of mats of various fibrous materials. One type of mat found especially suitable for the reinforcement of plastics because of the high fiber density obtainable comprises short lengths of strands of parallelly arranged glass fibers bonded to gether into substantially discrete bundles. These bundles of fibers may bein random lengths of from 1 inch to 3 inches but preferably all should be within the range of 1 /2 to 2% inches.

Masses of these fibrous bundles are deposited in the primary opened and fed to the picker rolls. The action of the picker rolls is such that the bundles of fibers are separated from one another without destroying the integrity of the individual bundle. The mat formed by the first picker section while substantially uniform in crosssection is reprocessed through a second set of rolls by which it is again disrupted and the bundles of fibers collected into a final mat of uniform density. A hinder .or impregnant may be applied to the mat by spraying or the like.

Glass wool fibers may be processed through the present apparatus either in the form of loose unbonded fibers or as the scrap from thermal insulating board manufacturing processes in which the fibers are compressed and bonded together into products of high density. In either case the fibers lie predominantly in planes parallel to the surface of the sheet or board. Processing this material through the present picker mechanism is accomplished by feeding the loose wool or boards directly into the picker rolls where the fibers are torn into tufts and collected in a sheet. This type of material while lacking in tensile strength as compared to the fibrous material previously described has been found suitable for thermal and acoustical insulation and provides a material in which the fibers extend in all directions.

The tensile strength of mats of the above material may be increased by concomitantly processing therewith continuous type textile glass fibers or strands. This is readily accomplished by distributing the continuous type fibers in the desired percentage by weight on the mass of wool fibers before processing and feeding the combined material through the rolls. For instance, a mixture of 80 per cent wool fibers and 20 per cent textile may be combined into a product having increased properties. In the final product the strands are randomly This mat when produced at a thickness of about one-half inch provides a suitable base material for roofing or the like and may be impregnated with the desired asphalt composi: tion and compressed.

Mats of very fine staple length glass fibers are produced in light densities of from 20 to 40 square feet per pound for thermal and acoustical insulation as well pression for a length of time.

as for padding and clothing interliner material. The individual fibers range in diameter from .00003 to .00015 inch and form a highly resilient mat. This material at times has a tendency to condense when held under com- This condition may be remedied by processing the previously formed mat through the present apparatus and including a small percentage of cut strands of continuous type fibers in the manner previously described. The strands which are bundles of fibers bonded together provide resistance to compression and prevent a matting together of the fibers. These strands of material may be added to the mat without materially otherwise altering any of its characteristics.

Organic fibrous materials including such vegetable fibers as ramie, jute, sisal hemp or cotton, and natural fibers such as wool, hair or fur may be processed by the present apparatus either alone or in any desired combination. Such inorganic fibrous materials as long or short fibered asbestos, rock wool or slag wool may also be processed and mixed with the organic fibers or glass fibers. Of the vegetable fibers ramie is preferred because of the greater fiber length and strength. These, as well as other fibers may be employed to provide bulk to glass fiber mats and conversely glass fibers may be employed to reinforce mats of ramie or other fibers.

Modifications may be resorted to without departing from the spirit of the invention or the scope of the appended claim.

I claim:

The method of processing fibrous material to form mats thereof which comprises distributing a mass of relatively coarse glass wool fibers in the form of a sheet, superposing thereon a layer of textile glass fiber strands, advancing the assembly of sheet and superposed. layer into a primary mixing stage, concomitantly comminuting said sheet and layer and discharging the comminuted material into the atmosphere within a confined zone, collecting the comminuted material into a felted sheet of substantially uniform thickness, advancing the felted sheet into a secondary mixing stage, comminuting said felted sheet to rearrange and redistribute the coarse glass fibers and textile glass fiber strands into a homogeneous mixture thereof, collecting the rearranged and redistributed material into a mat having a high degree of uniformity of composition in which the fibers and strands are haphazardly arranged and interfelted, applying a binder to the mat and curing the binder therein to preserve integrity of the material of the mat.

References Cited in the file of this patent UNITED STATES PATENTS 1,198,028 Harden Sept. 12, 1916 1,420,162 Toles June 20, 1922 1,542,559 Kopp June 16,. 1925 1,928,699 Neal Oct. 3, 1933 1,948,395 Powell Feb. 20, 1934 1,961,272 Williams June 5, 1934 1,970,742 Gerard et al. Aug. 21, 1934 2,233,433 Smith Mar. 4, 1941 2,467,291 Brelsford et al Apr. 12, 1949 2,528,091 Slayter Oct. 31, 1950 2,639,759 Simison May 26, 1953 

